Gonzalez Annette M, Cyrus Bita F, Muller William A
Department of Pathology, The Feinberg School of Medicine at Northwestern University, Chicago, Illinois.
Department of Pathology, The Feinberg School of Medicine at Northwestern University, Chicago, Illinois.
Am J Pathol. 2016 May;186(5):1387-402. doi: 10.1016/j.ajpath.2016.01.010. Epub 2016 Mar 8.
Leukocyte transendothelial migration (TEM) requires two major events: local dissociation of adherens junctions manifested as gaps in vascular endothelial (VE)-cadherin staining at the site of TEM and targeted trafficking of the lateral border recycling compartment (LBRC) to the site of TEM. However, the association between LBRC recycling and VE-cadherin gaps remains unknown. We found that when targeting of the LBRC is selectively inhibited using established methods, such as a function blocking anti-platelet endothelial cell adhesion molecule 1 antibody, depolymerizing microtubules, or microinjection of an antibody that inhibits kinesin, VE-cadherin gaps do not form around the blocked leukocyte. This is the first time that the LBRC has been implicated in this process. We obtained similar results for neutrophils and monocytes and in studies using live cell imaging microscopy conducted under fluid shear conditions. Depolymerizing microtubules did not affect the ability of leukocytes to induce tyrosine phosphorylation of VE-cadherin. A VE-cadherin double mutant (Y658F, Y731F) expressed in endothelial cells acted as a dominant negative and inhibited VE-cadherin gap formation and TEM, yet targeting of the LBRC still occurred. These data suggest that targeting of the LBRC to the site of TEM precedes VE-cadherin clearance. Recruitment of the LBRC may play a role in clearing VE-cadherin from the site of TEM.
白细胞跨内皮迁移（TEM）需要两个主要事件：黏附连接的局部解离，表现为TEM部位血管内皮（VE）-钙黏蛋白染色出现间隙，以及侧向边界回收区室（LBRC）靶向运输至TEM部位。然而，LBRC回收与VE-钙黏蛋白间隙之间的关联尚不清楚。我们发现，当使用既定方法选择性抑制LBRC的靶向运输时，如功能阻断抗血小板内皮细胞黏附分子1抗体、解聚微管或显微注射抑制驱动蛋白的抗体，被阻断的白细胞周围不会形成VE-钙黏蛋白间隙。这是首次发现LBRC参与这一过程。我们在中性粒细胞和单核细胞以及在流体剪切条件下进行的活细胞成像显微镜研究中也获得了类似结果。解聚微管并不影响白细胞诱导VE-钙黏蛋白酪氨酸磷酸化的能力。在内皮细胞中表达的VE-钙黏蛋白双突变体（Y658F，Y731F）起显性负性作用，抑制VE-钙黏蛋白间隙形成和TEM，但LBRC的靶向运输仍会发生。这些数据表明，LBRC靶向运输至TEM部位先于VE-钙黏蛋白清除。LBRC的募集可能在从TEM部位清除VE-钙黏蛋白中发挥作用。
